/*
*有一牧场，已知养牛27头，6天把草吃尽，养牛23头，9天把草吃尽。如果养牛21头，那么几天能把牧场上的草吃尽呢?并且牧场上的草是不断生长的。 */
public class Test {
    private int addNum;
    private int allNum = 0;
    private int dayNum;
    public static void main(String[] args) {
        Test test = new Test();
        test.sum();
    }
    public void sum (){
        while (27*6-6*addNum != 23*9-9*addNum){
            addNum++;
        }
        allNum = 27*6-6*addNum;
        while (21*dayNum-addNum*dayNum != allNum){
            dayNum++;
        }
        System.out.println(dayNum);
    }
}
